Industrial heating furnace



March 2, 1954 D HAZEN INDUSTRIAL HEATING FURNACE 2 Sheet sSheet 1 Filed July 20, 1951 March 2, 1954 HAZEN INDUSTRIAL HEATING FURNACE 2 Sheets-Sheet 2 Filed July 20, 1951 INVENTOR.

Patented Mar. 2, 1954 UNITED STATES ATENT OFFICE: I

INDUSTRIAL HEATING FURNACE Frank D. Hazen, Pittsburgh, Pa.

Application July 20, 1951, Serial N 0. 237,788

3 Claims. 1

This invention relates to new and useful improvements in industrial heating furnaces, more particularly to industrial heating furnaces of the recuperative type, and it is among the objects thereof to provide a combination continuous heating furnace and recuperator structure in which the recuperator parts are readily accessible for cleaning and maintenance work without requiring a complete cooling of the furnace and recuperator parts, thereby increasing the capacity of such furnaces.

It is a further object of the invention to provide industrial heating furnaces with recuperator structures disposed above the furnace to provide for the natural up-draft of the products of combustion of the furnace to assure maximum efficiency in combustion and uniform heating of the product.

The invention will become more apparent from a consideration of the accompanying drawings, constituting a part hereof, in which like reference characters designate like parts, and in which- Fig. 1 is a side elevational view, partially in cross-section, of a recuperator furnace structure embodying the principles of this invention;

Fig. 2 is a top plan view taken along the line 22, Fig. 1; and

Fig. 3 is a vertical cross-sectional view, partially in elevation taken along the line 3-3 of Fig. 1.

With reference to the several figures of the drawings, the numeral I generally designates the superstructure of the furnace as consisting of I-beams and channels for supporting the refractory walls and roof which constitutes nopart of the present invention; Numeral 2 designates'the hearth line on which material such as slabs or billets are moved from the charging end to the discharge end of th furnace, from left to right as viewed in Fig. l of the drawings. The arrows indicate the direction of flow of products of combustion from the firing zones which are established at intervals longitudinally of the furnace chamber. The numeral 3 designates the outlet passage of the products of combustion through the roof of the furnace which communicates with a recuperator chamber generally designated by the numeral 4.

Th recuperator structure may be supported on the furnace binding or it may be supported on separate steel work and comprises the usual refractory walls 5 which are entirely steel encased as shown at 6 to prevent leakage of the hot gase common to current types of recuperators,

and the bottom wall of the recuperator chamber is provided with bafiles generally designated by the numeral 1 in the path of the gases passing from the furnace outlet to a stack designated by the numeral 8. The stack is provided with a Venturi outlet 9 connected to a blower establishing a forced draft whereby the velocity of the products of combustion drawn from the furnace through the recuperator chamber may be regulated.

The recuperator consists of a series of metal tubes In which are suspended by flanges H from the roof l2 of the recuperator chamber. A plurality of inner tubes l3 are disposed on the tubes 10 extending to substantially the bottom of the tubes In and are suspended by flanges I4 from partition walls I5. The top of the outer and inner tubes l0 and I3, respectively, are enclosed. in header boxes l6 and I! which are more clearly shown in Fig. 3 of the drawing. The header box H is provided with a duct l8 for supplying cold air from a fan or blower, not shown, and the header box IE is provided with a hot air duct I9 from which preheated air is delivered to the furnace burners to commingle with the fuel deliv ered to the furnace chamber. As is also apparent from Figs. 2 and 3 of the drawings, there are double rows of tubes which are staggered so that the products of combustion passing from the furnace outlet 3 to the stack 8 travel a zig-zag path to provide maximum contact or wiping action with the recuperator tubes it. The baffles I prevent the gases from taking a direct path beneath th recuperator tubes to the stack.

Peep holes 20 are provided in therecuperator wall for the insertion of soot blowers or other cleaning means and gates or openings 2! may be provided for accessibility and for cleaning the floor of the recuperator structure. In operation the cold air drawn through the duct l8 into header I! passes downward through the inner tubes and then from the open bottom of the inner tubes into the annular space between the inner tube l3 and outer tube It and upward into the header box Hi, from which the highly heated air passes through duct It to the furnace.

By placing the recuperator structure above the furnace instead of below as in conventional r cuperative furnace construction, there is no down draft that would cause back pressure in the furnace chamber, and the natural draft or forced draft of the stack is available at the discharge end of the furnace to maintain efficient combustion and proper heat control of the slabs or billets passing along the furnace hearth 2.

The recuperator tubes In are accessible from the top of the recuperator and may be pulled vertically upward for replacement or repairs. One of the features of the invention is that the recuperator need not be cooled or shut down to make repairs to the tubes and the structure lends itself to ready cleaning to maintain the efliciency of the heat exchange tubes. Also the construction above the furnace provides unlimited space foif recuperate: area so that the maximum heat exchange is available for absorbing the heat from the hot products of combustion passing from the furnace to the stack. By the use of a fan for supplying cold air through theducts l 8 to the header I'l suflicient circulation of the and air through the recuperator tubes is maintained to create a temperature differential that will prevent the burning out of the nietal tubes which are preferably made of stainless steel. For example, assuming the temperature of the hot gases or productsof combustion passin through the recuperator t ater 4 to be 2900* ate the air circulating iroin the inner tube through the annulus and outer tube to the header is to be 1M6 when delivered the due s then the temperature of the tubes Deana be less than r500 This is because the tensity of the air blown through th inner is much greater thanthe velocity of the gases passing from the furnace outlet 3 through the recupe'rator ham a ae a a o. v I

. bi e de t miheebev d riiii i. t e invention that industrial heating furnaces hav: i s t r qrs m w esnmrs si th o r id a v i iei a d eqe em a-l, n s- T operatingsuch furnaces with the maximum of r he t ai emp 'a 'e n in in mu 5 of heat through the stack; It is further evi dent that said structures are readily accessible ib i l en n r a r s o p 1 m: tq imentp t e. five n h s b n. at and described, it will be evident to those skilled in the art that various mpdifications may be madein the details of construction without departing from the principles herein set forth.

1. In an industrial heating furnace; a relatively ens. he s ma erbe g' en e ends discharge h a t the res i weat s: of; a waste gas flue extending parallel to said chamber connected at the charging end of said chamberand having a n exhaust staci at the other end thereof, said flueconstituting a qham: ber for receiving banks of freely suspended heat exchange tubes and banks of suc h tubes so dis- 5 posed said fines in the path of the waste gas flow from the heating chamber to the stack, said banks of tubes consisting of transverse rows of tubes with the tubes in adjacent rows in staggered relation.

2. In an industrial heating furnace, a relatively long heating chamber having a charging and discharging opening at the respective ends thereof, a waste gas flue extending parallel to said chamber connected at the charging end of said chamber and having an exhaust stack at the other end thereof, said flue constituting a chamber for receiving banks of freely suspended heat exchange tubes and banks of such tubes so dispfised in said flues in the path of the waste gas jflowirom the heating chamber to the stack, said banks of arses consisting of transverse rows of tubes with the tubes in adjacent rows in staggered relation, the free ends of said suspended tubes being state's fitiiii the bottom of said flue and bafiie members extending from the bottom of the flue beyond the lower ends of the tubes to prevent stratification of the gas flow at the bottom of thfiii I H 4 I 3. In an industrial heating innit-es, a relatively long heating states; aving a charging and a dischar ifipeiii'ng at the respective ends tests: of, a waste sa nts extending parallel to said chambeiaboy the heating chamber having one end eonin'iuiiiatifig witfi and master adjaeii the emerging an thfdf and having a waste stack at the other end arise iliie whereby the products of combustion fiat infipdsit arisetions in the heating chamber sea 2 He to titt es an uninterrupted natural estate saw of gases to the stack} said flue constituting a t en; baa; receiving banked? ffelii suspended heat exchange time; are of statute so disassa s said fines in the tan er the was e flow from the heating masses to the stack said banks of tubes consisting of transverse row of sites with the tubes adjacent rats in staggered relation.

ANK i H A References Cited in the file of this patent UNI' TED theses 

